The CW, that fount of TV youth, beauty, and sometimes addictive preposterousness, would not be the first place you’d expect to find a historical costume drama about Mary, Queen of Scots. Showtime, Starz, maybe even History, but the home of pouting vampires and fatuous gossip girls?

And, yet, inexplicably here is “Reign,” which feels like a tween-targeted, TL;DR (
“too long; didn’t read”) version of 16th-century European history.

It’s hard to know where to begin describing the many ways in which “Reign” falls flat in its attempt to sex up history for its demo, which deserves better than this.

You could start with the “history” element itself, which was apparently more of a suggestion than a hard and fast guideline. The main thread that has been kept alive is that, as a political alliance, Mary (Adelaide Kane) has been betrothed to Prince Francis, future king of France (Toby Regbo), since childhood.

And then things get wacky with mysterious woods, attempted rapes to besmirch virtue, a quartet of giggly ladies-in-waiting, secret castle passages, and a hooded figure who looks straight out of Arkham asylum. And that’s before you throw in the scene where a lady-in-waiting — so aroused by watching a “bedding ceremony” — stops to pleasure herself in the middle of a hallway only to be interrupted by the king himself who offers his assistance.

REIGN

There is the youthifying and hunking up of Nostradamus (Rossif Sutherland). There is the invention of at least one character out of whole cloth in Sebastian (Torrance Coombs), the half-brother of Francis. He was introduced to create a love triangle for Mary and is called “Bash,” because . . . the CW. Additionally, the predominant accent — no matter the speaker — in 1557 France is vaguely British.

(If they miraculously get back to actual history, viewers shouldn’t get too attached to Francis. And he might want to keep his ears warm.)

Oddly enough, part of the problem with the pilot is how mild even the most outlandish elements seem. Queen Catherine (Megan Follows) schemes against Mary to protect her son on the advice of Nostradamus, but she does so without any campy grandiosity. Mary and Francis bicker about the future of their respective countries, but neither feels particularly invested. Mary is told by a silhouetted stranger that she’s in danger, but you wouldn’t know it by her unperturbed visage. The scene in which the ladies-in-waiting watch the “bedding” doesn’t feel risque but creepy, since they’re all teenagers.

With its grand castle backdrop and sumptuous costumes, “Reign” looks beautiful, as do all of the people in it. But there needs to be something a little more substantial — be it drama or kitsch — between those walls and seams to make “Reign” into a show worthy of ascending to the heights of guilty pleasure TV royalty.